Pyrazolidone electron transfer agents have been previously described for use as auxiliary developing agents in black-and-white and color photographic developers. It has been proposed to include these materials either in the developer solution or in the sensitized silver halide layer of a photographic film.
For example, U.S. Pat. No. 4,155,763 describes color developing solutions comprising an aromatic amine color developing agent and a 1-aryl-pyrazolidone having two substituents at the 4-position of the pyrazolidone. The advantages are said to include faster image dye formation and a more stable color developing solution.
The English language abstract of Japanese application 62/178251 describes a color developing solution comprising a para-phenylene color developing agent and an auxiliary developing agent including, inter alia, 1-phenyl pyrazolidone. Image formation is described as highly sensitive and forming excellent gradation.
WO 92/10789 describes the color development of an imagewise exposed photographic material in which the color development is carried out in the presence of one or a combination of black-and-white silver halide developing agents such as pyrazolidones, for example 1-(4-methoxyphenyl)-3-pyrazolidone, 1-(3,4-dimethoxyphenyl)-3-pyrazolidone and 1-phenyl-4-n-pentyl-pyrazolidone which provide acceptable sensitometric results with reduced variability.
When an electron transfer agent such as a pyrazolidone is incorporated in the sensitized layer, residual amounts can season into the developer solution and can affect other films which did not contain this material and which were not designed to be processed in its presence.
There is a need to solve this problem of the contamination of the developer solution by the presence of residual amounts of electron transfer agent when used for subsequent development.